title: Video enhanced imaging of the fluorescent Na+ probe SBFI indicates that colonic crypts absorb fluid by generating a hypertonic interstitial fluid.
abstract: Extracellular accumulation of Na+ detected by video-enhanced microscopic imaging of the impermeant fluorescent probe SBFI confirms the view that colonic crypts produce a hypertonic ascorbate ca 1000 mOsm.kg-1, thereby generating a large osmotic pressure across the crypt wall. This creates a high fluid tension within the crypt lumen, sufficient to dehydrate faeces. When bathed in Tyrode the SBFI.Na+ fluorescence indicates a [Na+] ca 750 mM within the interstitial space of metabolizing rat descending colon. There is no evidence of interstitial Na+ accumulation in octanol (2 mM) or in rabbit colon incubated with 1.0 mM ouabain and no evidence of Na+ secretion via the crypt lumen during absorption.
authors.affiliation: Department of Physiology, King's College London, England.
authors.forename: R J
authors.initials: RJ
authors.lastname: Naftalin
authors.forename: K C
authors.initials: KC
authors.lastname: Pedley
mesh_terms: D000818:Animals; D001572:Benzofurans; D003106:Colon / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004988:Ethers, Cyclic; D005110:Extracellular Space / Q000378:metabolism; D006982:Hypertonic Solutions / Q000378:metabolism; D007089:Image Enhancement; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008856:Microscopy, Fluorescence; D000442:Octanols / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010539:Permeability; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*
chemical_list: D001572:Benzofurans; D004988:Ethers, Cyclic; D006982:Hypertonic Solutions; D000442:Octanols; C061665:sodium-binding benzofuran isophthalate; D010042:Ouabain; D012964:Sodium